A motor/generator includes a rotor member, a shorting member and a stator. The rotor member has a plurality of permanent magnets. The shorting member is configured and arranged to selectively establish a short-circuit in magnetic flux of the permanent magnets to switch between a normal state in which the magnetic flux is not shorted and a shorted state in which the magnetic flux is shorted. The stator has a plurality of coils configured and arranged to be energized with a composite electrical current including first and second current components. The stator is further configured and arranged to form a first magnetic circuit between the coils and the permanent magnets with the first current component to drive the rotor member and to form a second magnetic circuit between the coils and the shorting member with the second current component to selectively switch between the normal state and the shorted state.